U.S. patent number 5,249,303 [Application Number 07/689,974] was granted by the patent office on 1993-09-28 for continuous reception by a mobile receiver unit of program channels transmitted by a series of transmitters.
Invention is credited to John D. Goeken.
United States Patent |
5,249,303 |
Goeken |
September 28, 1993 |
Continuous reception by a mobile receiver unit of program channels
transmitted by a series of transmitters
Abstract
A system and process for continuous reception of information by
a mobile receiver unit passing among a plurality of spaced
transmitters with each transmitter configured to individually
transmit signals to the mobile receiver unit. The mobile receiver
unit has a pair of scanning receivers controlled by a switching
control module. The module causes one of the scanning receivers to
lock onto signals transmitted from one of the transmitters while
causing the second scanning receiver to scan signals transmitted by
the transmitters in the reception range of the scanning receiver.
Once the strength of the signal locked onto by the first scanning
receiver falls below a predetermined minimum signal strength, the
second scanning receiver locks onto the best suited received signal
and the first scanning receiver is caused to commence scanning, the
roles of the scanning receivers thus being reversed. The process
continues, with the roles of the scanning receivers constantly
being reversed, as the mobile receiver unit traverses the signals
broadcast by the plurality of spaced transmitters.
Inventors: |
Goeken; John D. (Plainfield,
IL) |
Family
ID: |
24770585 |
Appl.
No.: |
07/689,974 |
Filed: |
April 23, 1991 |
Current U.S.
Class: |
455/431; 455/134;
455/140; 455/161.3; 455/525 |
Current CPC
Class: |
H04B
7/18506 (20130101); H04H 20/57 (20130101); H04H
20/26 (20130101) |
Current International
Class: |
H04B
7/185 (20060101); H04H 1/00 (20060101); H04B
001/16 (); H04B 007/26 () |
Field of
Search: |
;455/133-135,140,152.1,161.1,161.3,164.2,168.1,187.1,33.4,38.1,49.1,56.1,59 |
References Cited
[Referenced By]
U.S. Patent Documents
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4881273 |
November 1989 |
Koyama et al. |
4908839 |
March 1990 |
Morimoto et al. |
|
Foreign Patent Documents
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|
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|
|
|
|
0100528 |
|
Jun 1983 |
|
JP |
|
0122310 |
|
May 1988 |
|
JP |
|
0060115 |
|
Mar 1989 |
|
JP |
|
Primary Examiner: Eisenzopf; Reinhard J.
Assistant Examiner: Pham; Chi H.
Attorney, Agent or Firm: Lee, Mann, Smith, McWilliams,
Sweeney & Ohlson
Claims
What is claimed is:
1. A system for continuous reception of information by a mobile
receiver unit, comprising
a. a plurality of spaced transmitters each having means for
transmitting signals on a transmission channel, the transmitters
within a predetermined proximity to one another being configured to
transmit multiple program channels on non-interfering transmission
channels, said transmitters within a predetermined proximity
transmitting in transmission areas which at least partially
overlap,
b. a pair of scanning receivers in said mobile receiver unit, each
scanning receiver including means for scanning the transmission
channels transmitted by said transmitters, and
c. means for controlling said scanning receivers, said controlling
means including
i. means for causing one of said scanning receivers to lock onto
signals transmitted from a selected one of said transmitters,
ii. means for causing the second scanning receiver to scan the
transmission channels transmitted by said transmitters,
iii. means for comparing strength of said locked onto signals with
a predetermined minimum signal strength,
iv. means for causing the second scanning receiver to lock onto
signals received from a different selected one of said transmitters
when the strength of said first locked onto signals falls below
said predetermined minimum signal strength, and
v. means for causing said one scanning receiver to commence
scanning of the channels transmitted by said transmitters after the
second scanning receiver locks onto said signals received.
2. A system according to claim 1 in which at least some of said
transmitters each includes multiplexer means for transmitting
multiple program channels on the transmission channel of the
transmitter, and said mobile receiver unit includes a
de-multiplexer connected to said scanning receivers.
3. A system according to claim 1 in which said mobile receiver unit
includes a de-multiplexer connected through said controlling means
to each scanning receiver.
4. A system according to claim 1 in which each transmitter includes
means for encoding said signals, and in which the scanning means of
each scanning receiver includes means for recognizing only encoded
signals.
5. A system according to claim 1 in which each scanning receiver
includes means to log received channels when scanning.
6. A process for continuous reception of information by a mobile
receiver unit passing among a plurality of spaced transmitters,
each transmitter being configured to individually transmit signals
to the receiver unit, the transmitters within a predetermined
proximity to one another being configured to transmit multiple
program channels on non-interfering transmission channels, with the
transmitters within a predetermined proximity transmitting in
transmission areas which at least partially overlap, and the
receiver unit having a pair of scanning receivers each being
capable of scanning the signals transmitted by the transmitters,
the process comprising the steps of
a. causing one of the scanning receivers to lock onto signals
transmitted from a selected one of the transmitters,
b. causing the other scanning receiver to scan signals received
from said transmitters,
c. comparing the strength of the locked onto signals with a
predetermined minimum signal strength,
d. causing the second scanning receiver to lock onto signals
received from a different selected one of the transmitters when the
strength of the first locked onto signals falls below the
predetermined minimum signal strength, and
e. causing the first scanning receiver to commence scanning of
signals received from said transmitters after the second scanning
receiver locks onto signals received from the different selected
one of the transmitters.
7. A process according to claim 6 in which steps c through e are
repeated alternately between said scanning receivers such that one
scanning receiver is locked onto signals from one transmitter and
the other scanning receiver is scanning signals from other of the
transmitters.
8. A process according to claim 6 including an initial step, before
method step a, of causing both scanning receivers to scan signals
received from the transmitters.
9. A process according to claim 6 including, during method step b,
logging received signals from said transmitters.
10. A process according to claim 9 including logging received
signals exceeding a predetermined signal suitability.
11. A process according to claim 6 in which the signals transmitted
by each transmitter are multiplexed, and method step a includes
de-multiplexing the locked onto signals.
12. A process according to claim 6 in which the signals transmitted
by each transmitter are coded, and method steps a and d including
locking onto coded signals.
13. A process according to claim 12 in which method steps b and e
include scanning only of coded signals.
14. A process according to claim 9 in which the signals transmitted
by each transmitter are coded, and method steps a and d including
locking onto coded signals.
15. A process according to claim 14 in which method steps b and e
include scanning only of coded signals.
Description
BACKGROUND OF THE INVENTION
This invention relates to mobile reception of transmitted signals,
and in particular to a system and process for continuous reception
of information by a mobile receiver unit as the receiver unit
passes among a plurality of spaced transmitters.
Program material, live or recorded, may be sent to the mobile
receiver unit via radio, infrared or other means on a continuous
basis as the mobile receiver unit travels out of range of an
originating transmitter.
The present invention will be described primarily in relation to an
aircraft while airborne and travelling cross country while
receiving signals from transmitting ground stations. The invention,
however, is equally applicable to travel in automobiles, buses,
trains, water vessels, or any other conveyance in which reception
of program information without interruption is desired.
It has been estimated by one major United States airline company
that for each flight flown by the aircraft during a year, the
difference of one passenger on each flight translates into a
revenue difference of $170,000,000 annually. With increasing
competition and concentration in the airline industry, it is
imperative for an airline's survival that the airline provide
state-of-the-art services to attract passengers. Those providing
such services will experience growth of passenger revenue miles,
while those unable or unwilling to provide services demanded by
passengers and dictated by competition will see a decrease or
stagnation of growth, and eventual unprofitability and failure.
In providing passenger services, conveniences for the passenger are
paramount. For example, since about 1985, telephone service has
been available in some aircraft flying in United States airspace.
At first, telephones were available at only limited locations on a
limited number of aircraft. More recently, however, telephones in
some aircraft have been provided at seat back locations, thus
increasing convenience to the passenger and utilization of the
service, and thus generating additional revenue for the airline and
the provider of the telephone service.
Telephone service, however, is only a small portion of services
that could be provided to passengers. For example, news, sports
events, flight information, hotel information, gate information and
a myriad of other possible items of information and entertainment
could be provided to passengers to not only inform them, but also
reduce boredom on longer flights, thus increasing satisfaction of
the customer and leading to greater utilization of aircraft and
airlines providing such services.
The present invention is directed to receiving program information
and other relevant information by an aircraft (or other mobile
receiving unit) as it travels, without discernable interruption by
the user. Whether travelling on the ground, in the air, or on the
water, a mobile receiving unit operating in accordance with the
present invention can continuously receive information and provide
such information to passengers, crew, and anyone or anything else
desiring access to the information received.
SUMMARY OF THE INVENTION
The invention provides a system for continuous reception of
information by a mobile receiver unit. It includes a plurality of
spaced transmitters, each having means for transmitting signals on
a particular transmission channel, with the transmitters within a
predetermined proximity of one another being configured to transmit
signals on a continuous, non-interfering basis. A pair of scanning
receivers is located in each mobile receiver unit. Each scanning
receiver includes means for scanning the channels transmitted by
the transmitters for selection of one of the scanned channels.
Means is provided for controlling the scanning receivers, the
controlling means including means for causing one of the scanning
receivers to lock onto signals transmitted from a selected one of
the transmitters while the second scanning receiver is caused to
scan the channels transmitted by transmitters coming within
reception range. The controlling means also includes means for
comparing the strength of the signals locked onto by the first
scanning receiver with a predetermined minimum signal strength.
Means is provided in the controlling means for causing the second
scanning receiver to lock onto signals received from a different
selected one of the transmitters when the strength of the signals
locked onto by the first scanning receiver falls below the
predetermined minimum. At that point, the controlling means causes
the first scanning receiver to release its locked signal, and
commence scanning of the channels transmitted by the transmitters
of the network.
In accordance with the preferred form of the invention, at least
some of the transmitters each include multiplexer means for
transmitting multiple program and information channels on the
channel transmitted by the transmitter, and the mobile receiver
unit includes a de-multiplexer connected to the scanning receivers.
Also, each transmitter includes means for encoding the signals it
transmits, and the scanning receivers of the mobile receiver unit
include means for recognizing only the encoded signals. Preferably
also, each scanning receiver includes means to log received
channels when scanning, so long as the received channels have a
signal strength exceeding a predetermined minimum.
In accordance with the process of the invention, one of the
scanning receivers is caused to lock onto signals transmitted from
a selected one of the transmitters. The other scanning receiver is
caused to scan signals received from the transmitters as the
signals increase in signal level or come into the reception area of
the scanning receiver. The strength of the signals locked onto by
the first scanning receiver is continuously compared with a
predetermined minimum signal strength. When that minimum has been
reached, the second scanning receiver is caused to lock onto the
then best suited received signal based upon signal strength,
doppler shift and phase angle. At that time, the first scanning
receiver is released to commence scanning of signals received from
the transmitters so that, when the signal to this second scanning
receiver has been locked on falls below a predetermined minimum,
the first scanning receiver can be caused to lock onto a new,
stronger and better suited signal.
In accordance with the preferred form of the invention, initially
upon start-up, both of the scanning receivers are caused to scan
signals received from the transmitters. Only one of the scanning
receivers is caused to lock onto received signals after the initial
scanning.
To minimize the signals scanned by the scanning receiver that is in
the scanning mode, in accordance with the process of the invention,
only signals exceeding a predetermined signal strength are scanned.
Those signals with the proper identifying code are logged by the
scanning receiver, and when the strength of the signal received by
the non-scanning receiver has fallen below the predetermined
minimum, the strongest and best suited of the logged signals is
selected and the second scanning receiver is then locked onto that
signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail in the following
description of examples embodying the best mode of the invention,
taken in conjunction with the drawing figures, in which:
FIG. 1 is a schematic illustration of a ground transmitter for
transmitting signals to a mobile receiving unit, the figure
illustrating both single and multiple program channel
operation,
FIG. 2 is a schematic illustration of a mobile receiving unit
configured to receive signals from the transmitter of FIG. 1, and
including both single and multiple program channel receipt,
FIG. 3 is a graphic example of operation of the system and process
according to the invention, and
FIG. 4 is a schematic illustration of transmitting sites as
disposed across the United States to permit cross country air
receipt of program information.
DESCRIPTION OF EXAMPLES EMBODYING THE BEST MODE OF THE
INVENTION
As noted above, the present invention is described primarily in
relation to receipt of program information by an aircraft
travelling cross country. Thus, the following description speaks
largely in relation to air travel, using terminology such as
channels, radio signals, and the like. It will be evident to one
skilled in the art that the concepts of the invention are equally
applicable to all types of transmission. Such transmission may
include radio waves using any frequency or modulation, infrared
signals, microwave, light or any other means of transmitting a
signal.
FIG. 1 illustrates a typical ground station 10 according to the
invention. The ground station includes a signal transmitter 12
which transmits signals to the environment by means of an antenna
14. The transmitter receives signals for transmission in the form
of either a single channel input 16, or from a multiplexer 18,
which is fed multiple program channel inputs for transmission by
the transmitter 12. A plurality of the ground stations 10 are
employed, each ground station receiving its program channel or
channels via any conventional means, such as by wire, cable, fiber
optics, satellite, infrared, or otherwise. Since a plurality of
ground stations 10 are employed by the present invention, when
multiple program channel inputs are transmitted, it is necessary
that a specific program be assigned to the same multiplex channel
throughout the network of ground stations 10 for consistency
throughout the path of travel of any vehicle.
Preferably, each ground station 10 has its transmitter 12 coded to
identify the transmitter as a transmitter of a network of the
ground stations 10. Coding of the transmitted output from the
transmitter 12 can be by in band or out of band tones, or by any
other method which a mobile receiving unit can identify signals
from the transmitter as being from a transmitter of a network of
the ground stations 10.
In a typical ground station installation, each of the ground
stations 10 transmit signals radially to an aircraft for a distance
of approximately 250 miles depending on the altitude of the
aircraft. Thus, each ground station 10 has an extent of
approximately 500 miles through which a travelling aircraft can be
attached to the ground station for receipt of program information.
It will be evident that because the area encompassed by the signals
of a ground station 10 is circular, it is necessary due to the
various altitudes that aircraft fly that ground stations have
overlapping areas, not only for continuity throughout the area
being traversed, but also to assure that, as will be later evident
in the continuing description below, an appropriate ground station
is poised for selection once the signal strength of a ground
station locked onto has diminished below a particular signal
strength.
Each travelling aircraft includes one mobile receiving unit 20, as
illustrated in FIG. 2. Each mobile receiving unit 20 includes an
antenna 22 which, through a splitter 24, feeds received signals to
a pair of scanner receivers or scanning receivers 26. The scanner
receivers 26 are controlled by a switching control module 28, the
output of the switching control module then being either on a
single program channel output 30, if only a single channel is
broadcast and received, or from a de-multiplexer 32 if multiple
program channels are broadcast. Typically the de-multiplexer 32 is
used since multiple programs are received, and thus the line 30 is
eliminated.
The splitter 24 is a typical splitter which simply splits signals
from the antenna 22, sending identical signals to each of the
scanner receivers 26. Each of the receivers 26 is configured
conventionally to scan the frequency band used by each of the
ground stations 10. Each of the receivers 26 (or the switching
control module 28, discussed below) is configured to maintain a log
of signals received and the strength of those signals when the
signals exceed a predetermined level, along with other pertinent
data. Also, since the signals from each ground station 10 are
preferably coded, each of the scanner receivers 26 (or the
switching control module 28) also includes a decoder so that only
coded signals are recognized by each of the scanner receivers
26.
The switching control module 28, which may be a programmed computer
or a specially constructed module, controls operation of each of
the scanner receivers 26. The switching control module 28 is
configured to cause one of the scanning receivers 26 to lock onto
signals transmitted from one of the ground stations 10 while the
other scanner receiver 26 scans all signals from ground stations in
the proximity, logging the signals and their strength, doppler
shift and phase angle. The switching control module is configured
to compare the strength of the signals locked onto by the one
scanner receiver 26 with a predetermined minimum signal strength.
The comparison typically is on a signal-to-noise ratio basis, and
once the noise of the received signal exceeds a predetermined
minimum, the switching control module 28 is configured to cause the
second or scanning scanner receiver 26 to lock onto the best suited
signal being received by that scanner receiver at that time. The
switching control module 28 is configured to then release the first
scanning receiver from being locked onto the now-weak signal,
permitting that scanner receiver 26 to then begin scanning signals
received from the various ground stations 10 in the proximity.
Thus, the relationships of the two scanner receivers 26 are
controlled by the switching control module 28 such that one scanner
receiver 26 is locked onto signals received from one of the ground
stations 10, while the other scanner receiver 26 is scanning the
remaining ground stations 10 in the proximity to determine the best
suited signal for eventually locking onto a new signal once that
locked onto by the other scanner receiver 26 falls below a
predetermined minimum.
Initially, when flight just begins, the switching control module 28
causes both scanner receivers 26 to scan, and locks only one onto
the strongest signal received, allowing the other to continue
scanning. At all other times, one of the scanner receivers is
locked onto a signal while the other scans, and vice versa.
All of the elements 12, 14, 18, 22, 24, 26, 28 and 32 of the
invention can be well-known transmitters, scanner receivers, etc.
as the case may be, or can be configured specifically to perform
the various features and functions of the invention. Given the
description of the invention as contained herein, one skilled in
the art can readily assemble the elements of the invention to
produce the claimed results. Some examples of some such elements
are found in the applicant's U.S. Pat. No. 4,419,766, the
disclosure of which is incorporated herein by reference.
A simplistic example of operation of the invention is illustrated
in FIG. 3 with an aircraft 34 shown at four points of travel in
relation to four different ground stations 10. The direction of
flight of the aircraft 34 is shown by the arrow in the figure.
When the aircraft 34 is located at point 1, the switching control
module 28 of the mobile receiver unit 20 contained in the aircraft
34 causes one of the scanner receivers 26 to lock onto the first
ground station 10, identified by the letter "D". As the aircraft 34
progresses in its flight, the strength of the signal received by
the aircraft 34 first increases as the aircraft approaches ground
station D, and then begins to diminish as the aircraft progresses
beyond the ground station D. During the entire time, while the
switching control module 28 causes one of the scanner receivers 26
to be locked onto signals from the ground station D, the other
scanner receiver 26 is constantly scanning the signal strength of
other ground stations 10, including the ground station C next in
the path of the aircraft 34.
As the aircraft 34 reaches point 2 in its flight path, the signal
from the ground station D has diminished to the point where the
switching control module 28 recognizes that the signal falls below
a predetermined minimum. At point 2, the scanning scanner receiver
26 will have logged signals being received, including the best
signal as being that from ground station C. At point 2, therefore,
the switching control module 28 causes the second scanner receiver
26 to lock onto the ground station C. At the same time, the
switching control module 28 releases the first scanner receiver,
which was locked onto the ground station D, permitting the first
scanner receiver 26 to resume scanning of signal strength from
available ground stations 10.
As the aircraft 34 progresses, the signal strength of the ground
station C increases as the aircraft approaches the ground station,
and then decreases as the aircraft 34 progresses beyond the ground
station C. At point 3, the signal received from the ground station
C has fallen below the predetermined minimum, and the switching
control module 28 then causes the scanning scanner receiver 26 to
lock onto the strongest next signal, that emanating from ground
station B. The scanner receiver 26 locked onto ground station C is
then released to recommence scanning of signals from available
ground stations 10.
Again, as the aircraft progresses in its flight, the signal
received from the ground station B increases in strength as the
aircraft 34 approaches the ground station, and then begins to
diminish as the aircraft 34 leaves the proximity of the ground
station B. At point 4, again the signal received from the ground
station B falls below the predetermined minimum, and the switching
control module 28 of the mobile receiver unit 20 within the
aircraft 34 causes the scanning scanner receiver 26 to lock onto
ground station A, releasing the other scanner receiver 26 from
being locked onto ground station B to continue the process of
scanning available signals from ground stations 10 in the
proximity. This process is repeated throughout the flight path of
the aircraft 34.
In some areas, when transferring from the influence of one ground
station to another, the signal strength of the ground station to
which the switching control module 28 of the mobile receiver unit
20 of the aircraft 34 has locked onto may fall below the
predetermined minimum, but the signal strength received from the
next strongest ground station 10 may not be sufficiently strong. In
this instance, the switching control module 28 simply remains
locked onto the ground station 10 to which it has been locked until
signal strength from the next ground station 10 is sufficiently
strong for transfer to that ground station. In this manner, a
consistent flow of program or other information will continue
throughout the flight path of the aircraft 34.
Turning to FIG. 4, the transmission areas 36 of a series of ground
stations are illustrated. The present invention utilizes ground
stations transmitting in the 800 to 900 MHz range or other
frequency band. Different frequencies are transmitted by the
various ground stations 10, the numbers in FIG. 4 indicating a
particular assigned frequency for each transmission area 36. It is
clear from FIG. 4 that ground transmitters 10 within a
predetermined proximity to one another where signals can interfere
are assigned non-interfering channels. The channels can therefore
be repeated periodically so long as the same channel frequencies do
not overlap in any one area. In this manner, the entire country can
be blanketed adequately so that transmission loss does not occur.
For example, when travelling from Chicago to Denver, Chicago is
shown in FIG. 4 as transmitting on channel 2. An aircraft thus
would be locked onto channel 2, transferring typically to channel
12, then channel 7, then channel 3 and finally channel 12 when
reaching Denver. Similar transfer patterns would occur for other
travel routes.
It will be evident that the system according to the invention,
using common elements to perform the functions according to the
invention or custom designed elements which perform those
functions, provides a versatile system for permitting a mobile
unit, whether an airplane or other travelling entity, to travel
over great distances while receiving a continuous program flow of
voice, music, data, control signals, video or other communications.
Various changes can be made to the invention without departing from
the spirit thereof or scope of the following claims.
* * * * *